Icicle Spear is only learned through level-up by Shellder, at level 13. Icicle Spear has a power of 10 when used by Shellder and has a power of 15 if Shellder is evolved into Cloyster while knowing this move, due to Same Type Attack Bonus (lol commonly known as STAB!!!).

ok sorry for the excess of info but it sorta shows I know a lot about pkmn and can win this quiz!

Thunderbolt, Electric type, 100% accuracy.Flamethrower, Fire type, 100% accuracy.Ice Beam, Ice type, 100% accuracy.And, the one a slight bit different from the others (that is, the other three can cause special effects, this one can't) ...

This was the moveset from Diamond/Pearl. and besides, you didn't say that it had to be in order. (you should also double check things... from a guidebook and the internet. You know, you have to, in case you mistake something)